The subject matter of this disclosure is generally related to testing of wireless devices. A wide variety of wireless devices exist. Examples include but are not limited to mobile phones, base stations, wireless routers, cordless phones, personal digital assistants (PDAs), desktop computers, tablet computers, and laptop computers. Testing of a wireless device may be desirable for any of various reasons. For example, testing can be done in the development stage in order to determine whether a prototype wireless device functions as predicted. Testing may also be useful for determining whether production wireless devices perform within specifications. Testing is also performed to predict device performance and user experience, e.g. testing in a lab to predict what will happen in a real world situation.
Current generation cellular technology is referred to as 4G or LTE (Long Term Evolution). Extensions to the LTE specifications, commonly referred to as LTE-A, or LTE Advanced, are underway. LTE networks are designed to provide higher throughput to the user device and overall system relative to earlier technologies. MIMO (Multiple Input, Multiple Output) technology, for example, is one aspect of providing higher throughput in an LTE network. Another aspect is increasing the likelihood that the user device will be close to a cell site. It is understood that decreasing the distance between the user device and the base station cell site corresponds to improved signal to noise ratio, which enables the use of higher modulations that deliver more bits per hertz resulting in overall higher throughput as well as a more robust connection. One way to increase the likelihood that the user device will be close to a cell site is to deploy more cells, i.e., increase cell density. Increasing the density of traditional macro cells may be impractical due to the equipment expense and lack of suitable locations for deployment. However, small cells which are often deployed to reduce congestion and loading of a macro cell may be used to increase cell density. Small cells are similar to macro cells in that they function as a cellular base station via which user devices can attach to the network, but they differ from macro cells in other ways. For example, small cells tend to be less costly and physically smaller than macro cells. Also, small cells typically transmit at lower power levels than macro cells, e.g., from several watts to milli-watts of power. Consequently, small cells typically have a smaller operating range than macro cells. Further, the deployment of small cells is relatively simple and adaptable in comparison with macro cells, e.g., rather than being mounted on a tower small cells may be mounted on lamp posts, ceilings, or even placed on a table in a residential building, for example and without limitation. Small cells can be open to all users or they may be open to only a select group of users, e.g., a CSG (Closed Subscriber Group). A mix of macro and small cells operating on the same frequency is referred to as a “heterogeneous network.”
The planned proliferation of small cells and heterogeneous networks creates unique challenges for network operators and device manufacturers in terms of device performance and user experience. Within a given region such as that serviced by a macro cell, small cells are sometimes deployed where the population or density of users creates a need to mitigate loading on the macro cell and thus alleviate congestion. Examples include but are not limited to metro areas where people gather, other areas of high user concentration (airports, stadiums, etc.), in company or university campuses, and residential areas such as apartment buildings. Consequently, small cells may be deployed in clusters rather than evenly distributed within the region. Small cells may also be deployed in an uncoordinated and unplanned manner by end users and others, in addition to being deployed in a coordinated and planned manner by a network operator. Consequently, a wide variety of small cell deployments and heterogeneous network scenarios may be encountered in the real world. Network operators and device manufacturers have a need for the ability to perform tests in such cell deployments and heterogeneous network scenarios.